EXPERIMENTAL ANALYSIS OF ACOUSTIC EMISSION PROPAGATION VELOCITIES AND ENERGY ATTENUATION LAW OF P AND S WAVES IN WOOD USING IMPROVED TDOA MEASUREMENTS

Abstract

To explore the propagation law of AE signal in wood, the propagation velocity of P-wave and S-wave and the energy attenuation law of different frequency components were studied By PLB (pencil-lead break) tests. Firstly, an improvedtime-difference-of-arrival (TDOA)method was designed to determine the arrive time. Thepropagation velocities of P-wave and S-wave were calculated. Then, the Young's modulus was estimated by P-wave velocity. Finally, on thebasis of eliminating the influence of standing wave, the energy attenuation models were obtained by numerical fitting and wavelet decomposition. The results showed that the improved TDOA algorithm can calculate the propagation velocity of P-wave and S-wave at the same time through one test, and the P-wave velocity can be used to estimate the Young's modulus. P-wave propagated faster in soft wood, while S-wave propagated faster in hard wood. The higher thefrequency of AE signal, the faster the energy attenuation.